Attachment for augers



(No Model.)

, W. J. M. DOBSQN.

ATTACHMENT FOR AUGERS.

No. 413,316. Patented Oct; 22, 1889.:

. original small hole.

3! UNITED STATES PATENT OFFICE.

WILLIAM J. M. DOBSON, OFBROOKLYN, NEW YORK.

. ATTACHMENT FOR AUGERS.

SPECIFICATION forming part of Letters ZEatent N o. 413,316, dated October 22, 1889.

Application filed March 12, 1889- To all whom it may concern.-

Be it known thatL-WILLIAM J. M. DOBSON, of Brooklyn, Kings county, in the State of New York, have invented a certain new and useful Improvement in Attachments for Augers, of which the following is a specification.

My attachment is intended to facilitate the enlargement of the whole or a portion of the length of a hole after it has been bored. This is frequently necessary, and the absence of any hold for the screw-spur at the point of the anger in the act of reboring renders it so difficult that it may be called impracticable except by first filling the small hole by a plug of wood. Even With such filling and its attendant difficulties there is no assurance that the large auger used for the reboring will be directed exactly the same as the small one first used, and the result is liable to be imperfect.

My invention overcomes all diificulties, avoids the necessity for any plugging with Wood and any removal of the remainder of such plug after an enlargement of a portion of the length of a hole, and insures that the enlargement shall be exactly concentric to the I attain this by providing a block of a size and form to fit tightly in the small hole. In such block the screw-spur of the larger anger is engaged, and as the large anger, of the diameter required to produce the enlarged hole, is inserted and revolved the smooth round block travels ahead of it in the small hole and keeps it exactly guided.

In what I esteem the most complete form of the invention the block is of soft metal near its axis, and is prepared beforehand with a tapering hole without threads, and the hole is afterward threaded by the introduction of the screw-spur of the larger anger. This insures that the block shall accurately match the large auger on which it is used; but if care is taken to make the screw spur ofa certain size and pitch the block may be previously threaded to an exactly corresponding condition.

I propose to provide a set of myblocks, one or more for each size of auger used;

The term pilot may be applied to my block as indicating its function of guiding accurately the center of the large auger.

Serial No. 302,982. (No model.)

sider the best means of carrying out the in vention.

Figure 1 is an elevation of a portion of an anger equipped with my attachment in operation. The timber is shown in section. The remaining figures show. the block or pilot detached. Fig. 2 is a central vertical section. It shows the block before the screw-threads are formed. Fig. 3 is a corresponding view showing the completed block. or top view of the same. Figs. 5 and 6 are vertical central sections. They show modified forms of the invention.

Similar letters of reference indicate corresponding parts in all the figures Where they occur.

A is the twist, and a thescreW-spur, of an ordinary screw-auger. It will be understood that the twist has the diameter of the enlarged hole to be bored, and that the auger has the usual provisions-dips, &c.-for cutting away the Wood as it advances and making a cleancut cylindrical hole.

B is a round block of less diameter, engaged 011 illBSCl'GW-SIJLU' (t. hen the block B is removed, the auger A a may be used in the usual manner to bore fresh holes in wood and analogous material. When block B is applied and screwed tightly upon the spur a, the auger thus provided with a round smoothsurfaced block to precede it is ready to be used to enlarge a previously-formed hole. The block B should be of the same diameter as the previously-formed hole, or only a little less, so that as the auger with the attachment is turned the smooth round block B will traverse the previously-formed smaller hole and keep it exactly centered.

Referring to Fig. 8, B is a softunetal interior of the block 13, adapted to receive and be shaped by the screw-spur a. This soft-metal interior is cast within a previously-turned rim of brass or other harder metal. It is formed originally with a smooth tapering hole. lVhenthescreW-spur a is introduced, it causes its interior to conform thereto. The conformation may, if found expedient, be made very complete by forcibly turning the block upon the spur by the aid of pipe tongs or the like before the auger thus equipped is used.

Fig. 4 is a plan Fig. 5 shows a still larger proportion. of the block soft metal. In this form the hard brass is a thin shell forming nearly the entire eX- terion-not only the cylindrical or slightly- 5 tapered exterior, but also both the plane faces. The preferable form for the exterior in all constructions is a cylinder slightly tapered a the forward end.

Fig. 6 shows the whole block of homogene- IO ous metal.- It may be entirely brass or iron or steel threaded by the insertion of a taper tap or by other means to match the screwspur on which it is to be used. It may be entirely a soft metal.

In the latter case the 15 hole is preferably threaded beforehand; but

block tapered and smooth, and the metal soft enough to take the impression of the threads of any spur.

I provide notches or grooves b on the periphery of the block 13 to facilitate securing the block firmly upon the spur a.

I claim as my invention- 1. The round block B, having a tapering hole and a slightly-tapered exterior adapted to match on a screw-auger of larger diameter and to serve therewith, as herein specified.

2. The combination of a screw-auger A a, for boring Wood, and a round block 13 of less diameter, the latter being provided with a hole adapted to fit on the tapering screwpoint and to be readily applied and removed, as herein specified.

In testimony whereof I have hereunto set my hand, at New York city, New York, this 11th day of March, 1889, in the presence of two subscribing witnesses.

' WM. J. M. DOBSON.

Witnesses: CHAS. F. BARTER,

CHARLES R. SEARLE. 

